Overview of Reproduction
Reproduction is the process by which living things generate offspring. All plants and animals reproduce. Reproduction can be asexual or sexual. Asexual reproduction is the primary method of reproduction for many simple organisms and sexual reproduction is the primary method for most complex plants and animals, including human beings.
Types of organisms that reproduce asexually include certain bacteria, fungi, protists (tiny organisms that have both plant and animal characteristics; e.g., seaweed, algae, slime molds, amoebas, protozoa), plants (e.g., bulbs, tubers) and animals (e.g., flatworms, hydra [type of fresh-water animal]). Asexual reproduction requires only one individual organism (parent) and does not involve sex cells (also called germ cells or gametes). This method of reproduction results in offspring that are genetically identical to the parent organisms.
Types of asexual reproduction include fission, budding, and regeneration. In fission, a single organism divides into complete offspring that are identical to each other as well as to the parent organism. In budding, a mass of cells sprouts from and then breaks away from the parent organism to form an offspring. Regeneration involves the development of offspring from a part of the parent's body that has broken away.
Reproduction in human beings is sexual. Sexual reproduction involves male and female sex cells. Male sex cells are called spermatozoa, or sperm (singular is spermatozoon), and female sex cells are called ova, or eggs (singular is ovum). Sexual reproduction results in offspring with a mixture of genes inherited from both the male and the female (i.e., the parents).